The 2nd International Symposium on Collaterals to the Brain is a multidisciplinary scientific conference focused on collateral perfusion in acute and chronic neurovascular disorders. This proposal requests partial support for a conference with broad, long-term objectives that will advance current research on collateral perfusion, identify gaps and produce a consensus statement on critical topics related to collaterals in stroke. Mentoring junior investigators in this endeavor is a major emphasis of this unique meeting devoted to collaterals to the brain. Collateral perfusion of the brain is now recognized as a fundamental determinant of stroke risk, ischemic infarction, and reperfusion injury including hemorrhagic transformation, recovery and clinical outcome in virtually every acute and chronic ischemic disorder of the brain. This forum has been established to devote attention to this top research priority of NINDS. The aims of this conference will convene over 48 leading experts to debate critical aspects of this burgeoning field, with a total of 400 participants for a 2-day conference in an academic setting. The confirmed program is structured into 12 one-hour debate topics on reverse engineering collaterals, endorsing a systems biology approach. Public forum debate format will be utilized by teams of 2 experts to methodically reach consensus, culminating with publication of a detailed consensus statement on research in collateral perfusion. A moderated dinner seminar on reverse mentoring will reflect upon the 6 themes addressed throughout the symposium, covered by 6 junior investigators nominated for travel scholarships. Every effort will be made to encourage participation by postgraduate students and postdocs, to have parity in the numbers of women, and to include minorities and persons with disabilities. Measurable outcomes of conference goals will be assessed, evaluating the impact of this symposium on the NIH commitment to new investigators, translational stroke research and the NINDS PRG priority for studies on collateral perfusion. The significance of this proposal is underscored by the cultivation of a framework for novel research collaborations, mentoring of new investigators and improved clinical practice in this area, through a unique event, associated interactions and subsequent publication of a consensus statement. The health relatedness of this proposal is rooted in the discussions and research initiatives that address key priorities on the influential role of collaterals in the devastating disorder of stroke.